Batteries-what do you prefer and why.Personally always revert to wet lead acid starter type batteries-120AH-they seem for  primarily weekend sailing type useage to last for ever and are competitively priced if you go for general purpose truck/plant batteries.

My boat was equipped when I got it with a 110AH marine dual useage battery for starting and two 80AH dual useage for auxiliary.

All three have now died the two smaller ones after only about three years according to their date stamps.

Phil

Hi Phil

I don't think that there are necessarilly hard and fast answers as there are different solutions to different problems.

Mine is a motor boat and it is normally plugged into shore power at the marina and obviously the batteries are on charge whilst I am under way. I can use virtually all the kit I need to without the slightest worry. From what I can make out; leisure batteries are about half the cost of deep cycle batteries and will do about half of the cycles before berore they are knackered. The ammount of times I would need to put a big drain on a battery would be quite infrequent so leisure batteries suit me. I've also heard that having a boat on shore power and only having the bilge pump running occaisionally doesn't do deep cycle batteries an awful lot of good.

I think that the two 80 amp batteries may be a bit light because you can only discharge it to 50% before you risk damaging it but on the other hand it may be more than enough. After all, when batteries have a finite life, there is no point in paying for battery power that never got used.

You need to think of the balance of what will be draining your batteries and when and what will be charging them and when. Can you "manage" the battery drain better by house keeping? A sort of daft example is to forget the white wine and drink red wine because it doesn't have to be chilled which means you can switch your fridge off!

If you sit down and try to balance charging and discharging for your own specific usage the answers will become apparent. Then is really the time to talk to others.

Cheers

Chas

Actually I personally always return to typical lead acid starter batteries-I now have three 120AH and they seem to work well-they have only just gone up in price from around about £50 each to £65-its the dual type designed to both start and deep cycle which I inherited with the boat and have all died since getting it 3 years ago.Where in the past I have used deep cycling pure leisure batteries just for aux. use they have lasted well

Batteries are set to a single dedicated starter and two aux.-classic split charge with a split charge relay but are wired such that all or any can be diverted either way -to start or aux.

Phil

Hi Phil

What I meant by leisure batteries (rightly or wrongly) are the lead acid car / truck batteries as opposed to deep cycle or the dedicated mini start only type batteries although I know that some of the lead acid batteries are more suited to engine starting than others.

As far as I know (and I'm not a battery expert by any means) dedicated starter batteries have thin plates and will allow high current draw for short periods but do not like deep discharges and deep cycle batteries do not like high current draw.

I've not heard of the dual type you mentioned (other than a car / truck battery) but there are so many new types around.

If what you've got works; youve cracked it.

Gel batteries also seem to be a waste of money unless you've got a good reason for them to work upside down.

The Merlin Equipment web site has some good information.

Cheers

Chas

Having got my new batteries decided to investigate current cost of smart regulators-was very suprised to see how Sterling Products have fallen in price-their standard digital smart regulator can be had for about £85 delivered and their fan cooled heavy duty model comes in at about £110.

Phil

For most boats, the best answer seems to be truck batteries, the reason being that modern trucks are designed not only to need starting batteries, but need electrical power to run tail-lifts, cooling/refrigeration units heating units (Eberspacher units for sleeping cabs etc) so the actual use these batteries are put through is very similar to the needs on a boat, as these devices are usually run with the engine switched-off.

The battery companies have worked with the truck manufacturers and spent millions developing these multi use batteries. Not only that but the market is so large they cost little more than a car battery!

Thats interesting because thats what I swear by-now have three 120ah truck batteries-the one I just bought was £65 including VAT from a commercial vehicle factos-set up as above.It had never crossed my mind that they need to be flexible as per Davids message but realise thats why they are so good.

Other bit of info is that as well as smart regulators I checked out alternators-look at

www.mareng.co.uk

Who have a good range of 75 ACR alternators for about £120.-because as Sterling point out pointless having smart regulators without a good alternator-in fact I will probably invest in good alternator first!

Bear in mind that Alternators when they first appeared were rarely bigger than about 12 ACR!

Also remember you dont have to buy for engine type just to fit-

Phil

Re alternators

Go and have a good look at a car /truck scrap yard/parts recovery depot.

You'll be amazed at what they sell.

Brother picked up a Vauxhall alternator that was identical to his Volvo unit - cost £12 as opposed to £250!

Most Volvo's seem to use GM units, particularly on the bigger and older engines.

Some truck egines have very large capacity alternators.

David is spot on about Truck Batterys. I own a Mercedes truck with tail-lift and for last year due to problems in Latvia getting proper batterys - had to install biggest standard Wet batterys possible. To run the tail-lift - I had to have engine running to prevent discharging the batterys too low.

Truck batterys designed for such as my 6 litre engine start, tail-lift ops are exceptional batterys for boats - they can take the hammering that compromise leisure batterys NEVER can. Pricing is also usually based on A/Hr's and not brand names !

Leisure batterys - even the more modern compromise ones that can start an engine IMHO are only good for domestic purposes, I can remember trying to start my car engine in emergency with a caravan leisure battery - plates collapsed with the current load !

A post above is correct in the plate description .... thin hard plates for high ampage - but poor discharge capability. 50% is max you should aim for. Leisure / Deep discharge batterys are thicker softer plates that do not like providing high current, but can suffer deeper discharge. But therein lies a possible error - the difference in % discharge is not so great ... NO lead acid battery likes to discharge too low regardless of leisure / standard etc. So it's good idea to not push a leisure / compo battery to less than 40% charge........

Cheapest and generally good source of batterys ? Local breakers yards - they take batterys of crash cars and test them - good ones sold at anything up from £5 ..... I ran my cars in UK on them and had years of use without trouble.

My boat has just had it's start battery changed after 10 yrs use ..... yes that's right ... 10yrs. A Heavy Duty Diesel start battery designed for vans. About 85 A/hr and 700 CCA size. Replacement is 55 A/hr and 720 CCA car battery.

My domestic is sealed Leisure compo battery of 85 A/hr and I only ever connect to start when last start battery needed help at end of last season. This battery is about 4 yrs old and still in top notch.

Charging - I do not boost charge, I do not have any fancy bits except for a plain Maplins Charge splitter that is connected to a plain car charger. It feeds both batterys without batterys connecting to each other. Alternator is bog standard 45A as fitted to Perkins on Taxi's etc. My battery management system is the standard 1 - Both - 2 - Off switch. I sincerely believe that boosting batterys to as close to 100% as possible can shorten life ... I've been on boats with boosters and noted that near all - the batterys were getting warm from the boosted charge. I've even seen battery on one boat go Bang from it.

Later I will be swapping out the start battery for a 100 A/hr job before I cross baltic again .... but untill then my battery bank appears to serve well and for years without addition of any gizmos. Cheap and cheerful !!

Some may argue or disagree with my post and ideas - but my proof is in the pudding ! 10 years on standard battery ...

For what it is worth, my Father who was in Combined Ops in WWII and had a unit of RAF radio trucks - fiited with large numbers of batteries (he said they lasted 4 years and were still just fine)

He never ever bought new batteries or threw one out, every couple of years, he would empty out the electrolyte, hoze out the batteries with fresh water and then refill with new sulphuric acid and water to the correct specific gravity.

He never used voltmeters, just took the SG of the battery to determine its level of charge. One of his favourite batteries came out of a 1932 Lanchester car - he was still using it in his boat in the 1980s.

My father-in-law had one Cromwell Tank (WWII vintage) battery in his boat, 12v made of wood! Each of the cells was the average size of a car battery, massive, charged it once a year and never bothered having any charging system on his boat, yet used it to start his engine all season when it was over 40 years old!).

I rather feel we are being persuaded that we need all sorts of high tech charging kit when really what we need are high quality batteries which are big enough and have enough lead and electrolyte to do the job!

I suppose that the pressure is on to make batteries as small as possible, while boats have ever more power draining gizmos - fridges, pressurised water systems, even electric loo pumps, never mind the elctronics - which were unheard of even in the 1980s. Our first boat had a single, small car-type battery that did everything, and an old fashioned domestic fuse board that was repaired with fuse wire! But saloon lighting was minimal, and water had to be pumped by hand.

The current one is very much designed to be plugged into marina shore power to feed its huge appetite for volts. We are in the procedss of gradually weaning it off,(LEDs instead of halogen downlighters in the saloon, putting a hand pump option into the water system etc) so that we can go long distance cruising without taking a power station in tow.

He never used voltmeters, just took the SG of the battery to determine its level of charge.

Wonder how many people would know how to do that now? When I took my Old (General) radio exam one of the questions was what is the SG of a charged and a flat battery... the result was meant to be recorded in the radio log - I think weekly.

Still remember them over 20 yrs later! 1270 - charged, 1110 - flat

W.

Think battery charging is an art in itself-one of my batteries-the dual purpose 100ah(age unknown)decided to die on a cell-result it and the 120AH truck battery linked to it both went flatover the winter..It took alot of effort to get the 120AH back into form-holding about 12.5 volts.Have learned thru experience-trickle charge for 24 hrs-leave to settle for similar period and repeat process several times-after the first charge it would only hold about 11.9V;progressively increasing its holding capacity over several charges.Have read up on this realise that  that a battery is an electro chemical process.

As for the smart regulators the fact that Sterling himself says you must keep battery topped up is an immediate put off for me as most authorites would suggest that anything approaching battery boiling shortens their live.Anyway my present alternator(size unknown)seems quite capable of split charging my 3 batteries.

Having said this believe that many current generation cars with computer controlled management systems manage battery charging.

Phil

It's also ironic I had to replace the Jeep battery this weekend - £99 odd from Halfords - reduced to £67.05 with a trade card. Always considered Halfords overprice but they ended up (with discount) the cheapest by £32!

W.

BUT-I am guessing that battery for jeep is about 80/90AH?-my latest 120 AH truck battery cost the same-but of course these batteries will not fit designed to car battery trays.It was a friend of mine who got me into these batteries when running Landrovers with Perkins/Toyota engine conversions and the like in the days before 4x4s everywhere where your only choice was Landrover or Toyota.

Phil

Battery SG is still used today ... go to Halfords / other car shops and you can still buy a Hydrometer to test the SG. In fact nowadays the hydrometer is marked in red / yellow / green segments as well !

I agree with posts that todays regime is to cure problems of consumption by charging ... which in my opinion is a**e about face. I was happily adding to my boats gear and then it hit me ! Blimey the power need if I switched on this lot is mind boggling. So I started to look at alternatives. Why have a light for cabin that feeds from battery bank if LED dry-cell lights can do it .... as example.

Water - yes - I liked my electric pumped supply in the caravan I used to own ... but it's hand pump on boat ! To improve the system and allow "hands-free" - I'm considering changing to foot-operated water pump.

Careful observation of real needs and replacement of items can return your boat to meagre power needs quite easily.

Have to say the electric water pump or pressurised pump is something I appreciate-have a handpump as well by sink which I mainly use for cold drinking-but boat came with kitchen sink;toilet sink;aft cabin sink and shower all with HandC powered by a calorifier and pressuried pump.

Phil

Not sure what the AH is for it but the cranking 'power' is 550 Amps... 4.0 litre 6 cylinder engine

W.

Very interesting forum, I replaced my batteries 2 years ago. I have a 60hp Ford Tempest engine for which I fitted a 90ah cranking battery with 2 x 120ah deep cycle batteries which are ideally suited to regular shallow discharge and constant charging from either shore power batteries or my solar/wind combination charging facility.

One of the responsibilities of a good skipper is general boat management, and that involves good overall knowledge of the daily running requirments of the boat systems and "power managment" It has taken me a while to get to grips with the power burden of the essential systems and ensuring the batteries are matched to this and topped up accordingly. I have all of the batteries individually switched onto the general services bus bar and only tend to switch one battery in at a time and monitor the system volts, as it is inpractical to constantly check the SG of each cell, during normal use. I usually allow the "duty"battery to discharge to 60% befor changing over to a fresh unit, and only use the engine battery when running the engine, as I consider this battery as emergency use only.

I have found this system to work very well on 1-2 week cruises without the benifit of shore power and find that the combined charging facilities can cope adequately with normal cruising cycle of engine use, as very rarely do we have a days cruise without running the engine as support at some point during the trip.

Happy Sailing

Ian